diff --git a/db/constraints.sql b/db/constraints.sql
index b2a03684ca..9859a7e889 100644
--- a/db/constraints.sql
+++ b/db/constraints.sql
@@ -15,8 +15,9 @@ alter table user
     add index user_name(name),
     add index user_tot (total_credit desc),
         -- db_dump.C
-    add index user_avg (expavg_credit desc);
+    add index user_avg (expavg_credit desc),
         -- db_dump.C
+    add index user_email_time (email_addr_change_time);
 
 alter table team
     add unique(name),
diff --git a/html/inc/boinc_db.inc b/html/inc/boinc_db.inc
index ebaa5a635e..cf33585adb 100644
--- a/html/inc/boinc_db.inc
+++ b/html/inc/boinc_db.inc
@@ -187,7 +187,7 @@ class BoincUser {
     static function lookup_prev_email_addr($email_addr) {
         $email_addr = strtolower(BoincDb::escape_string($email_addr));
         $mytime = time() - 604800;
-        return self::lookup("previous_email_addr='$email_addr' and email_addr_change_time > $mytime");
+        return self::lookup("email_addr_change_time > $mytime and previous_email_addr='$email_addr'");
     }
     // name is not necessarily unique
     //
diff --git a/html/ops/db_update.php b/html/ops/db_update.php
index 874e57e89c..31fe2723e2 100644
--- a/html/ops/db_update.php
+++ b/html/ops/db_update.php
@@ -1107,6 +1107,7 @@ function update_4_19_2018() {
 	add column previous_email_addr varchar(254) not null default '',
 	add column email_addr_change_time double not null default 0
     ");
+    do_query("alter table user add index user_email_time (email_addr_change_time)");
 }
 
 // Updates are done automatically if you use "upgrade".